If you wish to divide large model to multiple workspaces (WS) you have to create new workspace in Toad Data Modeler first and then select objects that should be displayed on the WS. In certain situations, for example in case your table names contain logically defined prefixes, e.g. Forum_, Blog_, Store…etc. you might find useful another possibility – to select objects and create new WS for the selection. If you wish to try this alternative approach, download and import the Add To New Workspace.txg package to Toad Data Modeler.
Download: Add to new workspace package
After import you will be able to select entities, views and materialized views in Physical Model Explorer, right click any selected object and choose Add To New Workspace item from popup menu.
Specify New Workspace Name then and click Execute. New Workspace will be created and all the selected objects will appear on the Workspace.
New Workspace Blog:
One nice advantage of this macro is that you can execute the macro from Object Viewer also. If you wish to add entities with Forum_ and User_ prefixes, use Object Viewer to make the selection using filters and then right click any item from the selection. Popup menu opens and you can select the Add To New Workspace item again.
After you divide your model to various Workspaces I recommend you to click the Autolayout icon or run the Alphabetic Autolayout macro to rearrange objects on your newly created Workspaces.